The effects of substitutional tin (Sn) doping on the layered LiMnO2 cathode material for lithium-ion batteries

Lithium-ion batteries (LIBs) have emerged as a dominant force in global energy storage, powering electric vehicles (EVs), grid-scale storage systems, and consumer electronics. Their dominance stems for unparalleled advantages, including high operating voltage, high energy density, long cycle life, high power, efficiency, and eco-friendliness. As a result, LIBs have become the dominant power source in the rechargeable battery market. However, their performance is often hindered by Jahn-Teller distortion, which causes structural degradation. To address this, substitutional cation doping has been explored as a strategy to enhance structural stability, electrochemical performance, and conductivity. In this study, first-principles calculations combined with cluster expansion techniques were employed to investigate Sn-substituted layered LiMnO 2 (R-3m), generating 29 distinct phases. Among these, three stable configurations Li 4 MnSn 3 O 8 , Li 4 Mn 2 Sn 2 O 8 , and Li 4 Mn 3 SnO 8 were identified, with Li 4 Mn 3 SnO 8 exhibiting the highest thermodynamic stability, metallic behaviour, indicating superior electron conductivity and improved mechanical stability. Structural analysis revealed good agreement with previous studies. The substitution of Sn for Mn was found to be doubly beneficial: it enlarges lithium diffusion channels due to its larger ionic radius and critically modulates voltage characteristics, with excessive Sn leading to a sharp voltage increase. providing valuable insights for designing advanced, stable Li-rich Mn-based cathodes with optimized Sn substituting for next-generation batteries.